Ultrahigh Breakdown Field in Gallium (III) Oxide Dielectric Structure Fabricated by Novel Aerosol Deposition Method

Abstract

With the increasing demand for modern high-voltage electronic devices in electric vehicles and renewable-energy systems, power semiconductor devices with high breakdown fields are becoming essential. β-Gallium oxide (Ga₂O₃), which has a theoretical breakdown field of 8 MV cm⁻¹, is being studied as a next-generation power-switch material. However, realizing a breakdown field close to this theoretical value remains challenging. In this study, an aerosol deposition-manufactured Ga₂O₃ film boasting an extremely high breakdown field, achieved through thickness optimization, heat treatment, and a unique nozzle-tilting method, is developed. This study explores the effect of oxygen vacancies on the dielectric constant, breakdown field, and microstructure of Ga₂O₃ films. Through these methods, Ga₂O₃ films with a denser (98.88%) and uniform surface, made less affected by oxygen vacancies through nozzle tilting and post-annealing at 800 °C, are produced, resulting in appropriate dielectric constants (9.3 at 10 kHz), low leakage currents (5.8 × 10⁻¹¹A cm⁻² at 20 kV cm⁻¹), and a very high breakdown field of 5.5 MV cm⁻¹. The results of this study suggest that aerosol-deposited Ga₂O₃ layers have great potential to enable power switches with reliable switching.